Activation of human T cells with superantigen (staphylococcal enterotoxin B) and CD28 confers resistance to apoptosis via CD95

Ag recognition is an essential component for an effective T cell response. However, T cell activation is also subject to additional regulation by accessory molecules. CD28 provides essential costimulatory signals that allow T cells to proliferate, whereas molecules such as CTLA-4 and CD95 (Fas) appear to be negative regulators. Currently, which outcome predominates under conditions of antigenic challenge is poorly understood. In particular it has been suggested that one consequence of antigenic activation of T cells is the up-regulation of both CD95 and CD95 ligand, thereby exposing activated T cells to apoptotic death. We have investigated this possibility in normal human peripheral blood T cells triggered by the superantigen SEB either in the presence of endogenous APCs or transfectants expressing DR4 and CD80. In either case, we find that such activation does not expose the majority of T cells to anti-CD95-induced apoptosis as detected by annexin V externalization and DNA fragmentation. Furthermore, by phenotypically identifying, by flow cytometry, those cells that received both antigenic and costimulatory signals from those cells that did not, we observed that CD95-induced apoptosis was not seen in activated T cells receiving Ag and costimulatory signals via CD28. However, while not all T cells were stimulated by superantigen, CD95 expression was found to be homogeneously up-regulated, suggesting a mechanism whereby bystander cells might be made susceptible to CD95-induced death. We conclude that antigenic activation of T cells via the TCR and CD28 engagement provides protection from CD95-induced apoptosis.     

Distinct neutrophil C5a receptor inflammatory events in cows initiated by chemoattractant C5a and lipopolysaccharide around parturition and in mid lactation

In neutrophils, toll-like receptor and complement component 5a (C5a) signaling are critical pathways regulating innate immunity. In cows, not much is known about the second C5a receptor, complement component 5a receptor 2 (C5AR2). It is an interesting player in sepsis treatment because it is considered to have an anti-inflammatory effect during normal inflammation. Periparturient cows are prone to severe infections, and the objectives of this study were to investigate the expression and functionality of C5AR2 during peripartum. We investigated the effect of 2 major inflammatory stimuli, C5a and lipopolysaccharide (LPS), on the expression of a selected number of genes (C5AR1, C5AR2, TLR4, ITGAM, COX2, and CXCL8) and functions linked to these receptors. Overall, TLR4, ITGAM, and C5AR2, all of which are involved in early inflammation, showed a lower expression in periparturient cows. However, an overall lower expression seems not to be the only explanation for the increased risk of sepsis in periparturient cows. Normally, in response to inflammation and as seen in the mid-lactation group, the expression of these genes increases after stimulation with LPS. However, in periparturient cows, stimulation with LPS led to a decrease in expression of these receptors, indicating a different response of neutrophils in response to LPS during this period. A decrease in ITGAM (coding for CD11b) expression complicates correct neutrophil localization and phagocytosis. Its downregulation upon stimulation might be detrimental for adequate eradication of the pathogen and might increase the risk of an imbalanced inflammation; C5AR2 seems to play a central role in this altered response. In addition, myeloperoxidase (MPO) activity in periparturient cows is lower in response to C5a stimulation. It has been suggested that MPO plays an important role in neutrophil shutdown and, thereby, timely resolution of inflammation. A decreased MPO activity might thus prolong the inflammatory reaction of the neutrophils. This finding was supported by the increased viability of the neutrophils obtained from periparturient cows. Even after stimulation, we found a lower caspase-3 activity in this group, indicating that they might be activated for a longer time compared with the neutrophils from mid-lactation cows. Accordingly, these alterations might contribute to a temporal mismatch in inflammatory responses, as often seen in severe periparturient infections.     

Calculation of the phase envelope of multicomponent mixtures with the bead spring method

A robust numerical scheme for the calculation of constant composition (isoplethic) phase diagrams of complex multicomponent mixtures is presented. The scheme refers to the sequential calculation of the phase envelope of a mixture by guiding the estimation for the equilibrium curve via the introduction of a “spring” that sets the slope value of the modified tangent plane distance with respect to either temperature or pressure. A simple variation of the proposed method allows direct estimation of the Cricondentherm and/or Cricondenbar points, thus avoiding the calculation of the entire phase diagram. Extensive tests of the proposed scheme for different types of phase diagrams, using both cubic and higher‐order equations of state are presented. © 2015 American Institute of Chemical Engineers AIChE J, 62: 868–879, 2016     

Thermodynamic and transport property models for carbon capture and sequestration (CCS) processes with emphasis on CO2 transport

Carbon capture and sequestration (CCS) is one of the most promising technologies for the reduction of carbon dioxide (CO₂) concentration in the atmosphere, so that global warming can be controlled and eventually eliminated. A crucial part in the CCS process design is the model that is used to calculate the physical properties (thermodynamic, transport etc.) of pure CO₂ and CO₂ mixtures with other components.     

Positive and negative regulation of human T cell activation mediated by the CTLA-4/CD28 ligand CD80

CD28 and CTLA-4 are related receptors that differentially regulate T cell activation. Despite the fact that they bind the same ligands, CD28 is a classical costimulator enhancing proliferation whereas CTLA-4 appears to perform negative regulatory functions. In this study, we have utilized the natural ligand for CD28 and CTLA-4 (CD80) to determine under what circumstances positive and negative effects are operative. We show here that the stimulation of purified human T cells with phorbol ester and ionomycin is inhibited in the presence of Chinese hamster ovary (CHO) cells expressing CD80. This inhibition is reversed by blocking with both anti-CD80 or Fab fragments of anti-CTLA-4 but also requires CD28 engagement. Furthermore, we show that the inhibitory function of CD80 requires elevated intracellular calcium since inhibition was observed only in the presence of ionomycin. In the absence of intracellular calcium elevation, CTLA-4 was not expressed at the cell surface, and CD80 acted positively as a costimulator of T cells, via CD28. These results demonstrate that the natural ligand CD80 can either costimulate or inhibit T cell responses depending on the conditions of T cell stimulation.     

End‐of‐life Solutions for Fibre and Bio‐based Packaging Materials in Europe

Efficient end‐of‐life solutions play an important role in developing sustainable packaging because they contribute to reducing resource wastage and environmental impact, whilst providing economic and social benefits. This paper briefly reviews current end‐of‐life solutions for fibre and bio‐based materials for packaging in Europe. It also addresses current research in the field, as well as standardization, legislation and socio‐economic aspects related to renewable packaging in Europe. This review focuses on the following groups of packaging materials: paper and board and bioplastics. With this hierarchy, recycling, organic recovery and energy recovery are analysed with regard to the processes and technologies that offer the most sustainable end‐of‐life options. Copyright © 2012 John Wiley & Sons, Ltd.     

Bilateral idiopathic macular pucker: a case report

BACKGROUND: Idiopathic epiretinal membrane or macular pucker is a common disorder which typically affects older individuals. Contraction of epiretinal tissue causes changes to occur in the underlying retina stimulating the appearance of a macular hole. This paper presents a case of bilateral macular pucker with accompanying pseudohole. The diagnosis, pathophysiology and management are discussed. METHODS: A 68-year-old male was examined for decreased vision in both eyes. Relevant ophthalmoscopic findings included macular changes compatible with surface wrinkling maculopathy. RESULTS: The patient was diagnosed with bilateral epiretinal membranes with accompanying pseudoholes. The diagnosis was confirmed by fluorescein angiography. Since the patient's vision loss was minimal, the need for surgery was precluded. The patient was to be monitored routinely. CONCLUSIONS: Macular pucker, the most common of acquired macular disorders, has become an important clinical entity. Recognizing distinguishing features, especially in cases associated with pseudohole, will allow more precise diagnostic and prognostic patient counseling. Regular follow-up examinations of patients with mild visual loss become important, because they permit optimal time for surgical intervention.